Thread drying apparatus



May 22, 1956 w. BAKKER THREAD DRYING APPARATUS 2 Sheets-Sheet 1 Original Filed Sept. 27, 1950 BY 4% E? ATTORNEY United States Patent O i THREAD DRYING APPARATUS Willem Bakker, Arnhem, Netherlands, assignor to American Enka Corporation, Enka, N. C., a corporation of Delaware Original application September 27, 1950, Serial No. 187,022. Divided and this application July 8, 1953, Serial No. 366,804

Claims priority, application Netherlands October 25, 1949 Claims. (Cl. 34-68) This application is a division of my copending application Serial No. 187,022, filed September 27, 1950.

The present invention relates to the drying of yarns and more particularly to an apparatus for the continuous drying of a plurality of yarns in sheet form.

When rayon is produced by the process described in Heim Patent No. 2,334,325, a plurality of yarns are spun simultaneously and these yarns, after spinning, are combined in closely spaced parallel relationship to define a sheet. The sheet is subjected to such aftertreatments as may be required and is then dried.

In the past it has been customary to dry yarns in sheet form by passing the sheet over heated rollers or to dry the yarns while they are freely suspended in hot air. While both of these proposals for the drying of yarns present some advantages, they likewise involve disadvantages which have heretofore militated against the more widespread use of the sheet continuous process,

In passing a sheet of closely spaced yarns across drying drums or rollers mutual sticking of component filaments of a yarn may occur and thus cause fiats in the yarn which deleteriously affect its quality. Furthermore, in a roller drying system it is hardly possible to afford opportunity for adequate thread or yarn shrinkage even when successive rollers of the system are driven at different speeds in an attempt at shrinkage compensatron.

In drying freely suspended yarns in sheet form, it is diflicult to distrbute the heated air efficiently and to dry at a uniform rate a large number of parallel yarns moving at high speed.

It is therefore an object of this invention to provide for the drying of sheet form yarns under high speed conditions while avoiding damage to the yarns, non-uniformity and inadequate shrinkage compensation.

A further object of the present invention is to provide apparatus for the drying of yarns in sheet form that are characterized by the production of high quality fully shrunk yarn under condition of good plant economy and low heat loss.

According to the present invention it is proposed to pass the sheet of yarns through slit-shaped zones and there to subject them to the action of gases which are heated to suitable temperature before delivery to the drying zone and are passed through the zone in a direction opposite to the direction of movement of the component yarns of the sheet.

Other objects and advantages of this invention will be apparent upon consideration of the following detailed description of a preferred embodiment thereof inconjunction with the annexed drawings, wherein:

Figure l is a view in vertical section of drying apparatus constructed according to the principles of the present invention;

Figure 2 is a view in horizontal section taken on the line 2-2 of Figure 1; 1

Figure 3 is a view in transverse section taken on the line 3-3 of Figure 1, showing, in broken lines, the man- 2,746,169 Patented May 22, 1956 ner in which the drying chamber is opened to permit threading up;

Figure 4 is a longitudinal section of a drying chamber according to this invention showing heat radiating plates and the means for heating them; and,

Figure 5 is a view in transverse section taken on the line 55 of Figure 4.

Referring now in detail to Figures 1 and 2, the numeral 10 represents a draw-off roller which acts to withdraw the sheet of yarns from a source such as an aftertreatment bath and to deliver the sheet to a propulsion system comprised of rollers 11, 12 and 13 which together function to deliver the sheet to drying. The rollers 12 and 13 additionally act as press rollers to squeeze any residual aftertreating liquid or water from the yarns as they pass to drying.

After leaving the rollers 12 and 13 the sheet of yarns passes to drying chambers 14 and 15, through them and to take-up roller 16.

It will be observed that the drying chambers 14 and 15 are internally narrow in the vertical direction and contoured to accommodate the sheet of yarns with very little waste space. Within the chambers 14 and 15 the yarns are guided by combs 17, 18 and 19 and by groups of bars 20 and 21.

The combs 17, 18 and 19 are alike in construction so that an explanation of the structure and function of one of them will sufiice for all. In Figure 3, the comb 18 is more fully illustrated, and that comb will be described in detail with the understanding that the same considerations apply to combs 17 and 19.

The comb 18 comprises a number of teeth 29 anchored in a bar 39 which is, in turn, countersunk in a comb bridge 31. The teeth 2? are arranged in two parallel rows extending in spaced relation adjacent opposite long edges of the bar 3%) and, between the two rows of teeth there is located another bar 33 which rests on the bar 30 or forms a part of it, and extends upwardly from the plane of the base of the teeth a distance much less than the height of the teeth. At one end 34 of this bar 33 there is hinged to it a safety bar 35 which, with the bar 33, defines a thread space between each adjacent pair of teeth. Note in this regard that the teeth 29 on opposite sides of the bars 33-35 are arranged in staggered relationship.

In view of the fact that the function of the bar 35 is that of a retainer to keep the yarns from riding out of their position between teeth 29, a spring lock 36 is provided at the end of the safety bar 35 remote from the hinge 34. The spring lock 36 projects up from the bar 30 and provides a detent 37 which projects above the top surface of the safety bar when that bar is in the full line position of Figure 3.

In threading up the various combs 17, 18 and 19, they are moved from the normal operating position which is shown in full lines in Figure 3 to the broken line position of that figure in which they hang down vertically. In order to move the comb from the full line position of Figure 3 to the broken line position of that figure it is apparently necessary to move away the bottoms of the drying chambers 14 and 15. To this end the drying chamber 15 is made of two parts, an upper part 38 and a lower part 39. The lower part 39 has a peripheral flange 3? which seats in sealing engagement against the lower edge of the upper portion 38. At spaced points on the bottom surface of the lower portion 39 of the drying chamber 15, there are provided ears 40 and 41. Similar ears 42 and 43 are provided on the bottom 44 of the drying chamber 14. The upper portion of the drying chamber 14 bears reference numeral 45 and the structure of the two drying chambers 14 and 15 is so similar that a description of one will suflice for both.

Because of the position of the section line from which Figure 3 is taken, that figure shoWS an edge of the bottom portion 39 and the top portion 33 of the chamber but shows ear 43 and the hinging arrangements for the chamber 14. Since the bottom portions 39 and 44 of the chambers 14 and 15 are coupled together at the comb 18, it is apparent that when any one of the combs 17, 18 or 19 is to be threaded, both bottom portions 44 and 39 must be let down simultaneously. A description of the mechanism by which the bottom portions are let down can be understood by a description of the mechanism associated with car 43, that mechanism showing in Figure 3. It will be understood that a similar mechanism is associated with each of the ears 40, 41 and 42.

There is a bent bar 46 which is pivotally attached at one end to the car 43 and at the other end to an ear 47 which projects from the upper portion 45 of the drying chamber 14. By this arrangement it is possible to pivot the entire bottom portion of the drying chamber from the full line position of Figure 3 to the broken line position of that figure so that all of the combs may be rendered accessible for threading. The comb 18 is pivoted to a bracket 48 and the axis of that pivot lies closer to the drying chamber than the axis of the pivot between the bar 46 and the ear 47 so that the two may pivot independently without interference. It will be observed that brackets 49 are associated with the comb 17 and brackets 50 with the comb 19 and that bottom portion pivoting assemblies similar to the one shown in Figure 3 are associated with each of the ears 40, 41 and 42. See in this regard Figures 1 and 2. Suitable locks not shown are used to hold the lower portions 39 and 44 in their operating position.

Between the combs 17, 18 and 19, which guide the individual threads making up the sheet, there are located vertically staggered bars which serve to locate the sheet itself within the drying chambers. The mounting of these bars can be easily understood by reference to Figures 1 and 2. The upper bars are mounted from the side walls of the upper portions 38 and 45 of the chambers 14 and 15 and the lower bars 21 are mounted in brackets extending upwardly from the floor of the bottom portions 39 and 44 of the drying chambers. These brackets show in side elevation and are indicated in Figure 1 by reference numerals 51 and 52. The same brackets show in plan in Figure 2.

The steps to be taken by an operator in threading up the drying apparatus can now be understood. The operator approaches the machine from the front side which, according to the illustration, is at the bottom of the sheet containing Figures 1 and 2, and releases the bottom portions 39 and 44 so that they simultaneously fall and extend vertically from the back of the machine. This can be understood by reference to Figure 3. A sheet of threads running in a horizontal plane between the rollers 12-13 and 16 is established and it will be understood that that sheet is running in a horizontal plane under the upper portions of the chambers 14 and 15. The operator then grasps the thread nearest to him and puts it under the lowermost tooth of each comb. He repeats this operation for the next to lowermost teeth and so forth until all of the teeth of all of the combs are threaded. At this time the sheet of yarns lies in a vertical plane and the individual yarns are kept from displacement because of the slope of the comb teeth. Note that they slope downwardly at their points when they hang in the vertical position as can be seen in Figure 3. The safety bar is next latched in position and the combs are swung up to hori zontal position and latched with the detent 37. As they are moved up, the yarns move with them and the support which the sheet gets from the bars 20 and 21 is accomplished automatically since the bars 21 come into position under the sheet when the lower portions 39 and 44 are swung into position. The sheet was initially established under the bars 20 and it stays that way.

Thus far the description of the drying chambers has l been concerned yery largely with the combs and with the lower portions 39 and 44. It is through the stationary upper portions, however, that the gaseous medium for drying the sheet of yarns is applied. In Figure 1 there is shown for the chamber 14 an intake conduit 53 and an exhaust conduit 54 while, for the chamber 15, there is shown an intake conduit 55 and an exhaust conduit 56. The conduits 53 and 55 are connected to a source of hot air and that air is circulated contra to the direction of thread movement through the two chambers and exhausted respectively through the conduits 54 and 56.

In Figure 5 there is shown a modified arrangement in which auxiliary heat is introduced into the drying chambers to augment the heat supplied through the conduits.

In Figure 4 the direction of thread travel is indicated by an arrow and arrows associated with conduits 5'7 and 58 indicate the direction of flow of the gaseous drying medium through the drying chamber. The drying chamber itself is unnumbered in Figure 4 but corresponds in structure and in function to the drying chambers 14 and 15 except that overlying the upper central portion of the chamber there are provided radiation elements or plates 59 and 60 which extend across the width of the chamber and which are heated for example by gas supplied through elongated burners such as the burners 61 and 62 shown in Figure 4. The flames from the burners 61 and 62 heat respectively the plates 59 and 6% which in turn provide radiant heat to the thread and a heat exchange surface to the drying medium passing through the drying chamber, the heat exchange surface being actually the upper surface 63 of the drying chamber on which the heated elements 59 and 60 rest. A hood 64 surrounds the burners 61 and 62 and the elements which they heat and the products of combustion are taken off through a conduit 65. Oxygen to support the combustion can be supplied through the conduits 6?. and 62 through air vents in the hood which are not shown or the plates 59 and 60 may be electrically heated, in which case the hood may be entirely removed.

It will be understood that as the sheet of yarns moves from left to right in Figure 1, the drying will occur progressively, that is, the threads will contain the most liquid in the left-hand entrance to the chamber 14 and will be dry when they leave the chamber 15. It is desirable, therefore, not only that the gases which accomplish the drying be run countercurrent to the direction of move ment of the sheet but also that the gases at the highest temperature contact the wettest thread and that gases at a lower temperature contact the thread after it has been somewhat dried. Consequently, it is proposed, as a part of this invention, to introduce gases through the conduit 55 at a lower temperature than through the conduit 53. As a matter of fact, the gases exhausting from the conduit 56 can be additionally heated and then introduced into the conduit 53. While the arrangement shown in Figure 1 involves but two drying zones, it is of course possible to provide a plurality of such zones in excess of two and to maintain in the series of zones temperature variations with the highest temperature in the first zone into which the sheet passes and the lowest temperature in the last zone through which it passes. If the same gases are passed in series through the entire apparatus from the last zone which the sheet contacts to the first, the highly heated exhaust from the first zone can be used to preheat the air admitted to the last zone. If, for example, three zones are involved, the temperature at the first zone might be 150 C., that at the middle zone 120 C., and that at the last zone, C. It is of course not necessary to recirculate the heating gases and fresh heated air can be admitted to each zone if desired.

The radiation heater of the type shown in Figures 4 and 5 is intended for use in the early stages of the drying where higher temperatures are maintained.

The speed of the delivery rollers 12 and 13 is very accurately controlled and the speed of the take-up device 16 is adjustable in such a way that the tension throughout the drying zone is accurately controllable with resulting good control of shrinkage. As a matter of fact, viscose rayon threads can be well dried at speeds even in excess of 100 meters a minute by the use of the methods and apparatus of the present invention.

It can be seen that the use of wide long drying chambers with small height allows for economy in the drying gases, uniform contact between the yarns and the drying gases and easy maintenance. The standards which support the upper members 14 and 15 are widely spaced and located in such a way as to avoid interference with the operation of the lower portions 39 and 44 during threading.

A suction device 66 is diagrammatically indicated in Figures 1 and 2 and this device is for the purpose of collecting the running end of any yarn that may break so as to avoid fouling within the drying chambers.

Upon reference to Figure 3 it will be noted that the lower side or" the comb bridges 31 lies in the plane of the upper surface of the peripheral flanges 48. Thus, the comb bridge lies in the sealing plane between the upper and lower portions of the drying chamber.

While throughout the specification frequent reference has been made to a sheet of threads moving in a horizontal plane and to the horizontal disposition of the bottom portions of the drying zones, it is to be understood that neither the sheet nor the bottom portions need be perfectly horizontal so long as they are substantially parallel.

While the take-up device 16 has been shown somewhat diagrammatically, it is to be understood that the output from the drier may be collected on a beam or the individual threads may be wound or twisted.

What is claimed is:

1. Apparatus for drying yarns running in parallel relationship in sheet form that comprises a chamber having an upper portion and a lower portion together defining a long internal space of a width not substantially in excess of the width of the sheet to be accommodated and of small vertical height, combs extending across the chamber for guiding the yarns of the sheet, means pivotally mounting said combs at one end to said upper portion for movement from a horizontal position to a vertical position, means pivotally mounting said lower portion for movement from an upper horizontal position defining a chamber to a vertical pendant position whereby the combs may be moved to vertical position for threading and moved back to horizontal position in use and means to supply heating gases to said chamber through the upper portion thereof.

2. Apparatus for drying yarns running in parallel relationship in sheet form that comprises a chamber having a long internal space of a Width not substantially in excess of the width of the sheet to be accommodated and having small vertical height, means to guide the yarns of the sheet within said chamber, means to admit a heating gas at a higher temperature to the wettest yarns and means to admit a heating gas at a lower temperature to the partially dried yarns, means to withdraw the heating gases after they have been passed in countercurrent relation to the direction of movement of the yarns, a plurality of radiation plates extending lengthwise of the top of said chamber between said admission means and said Withdrawal means, a hood covering said radiation plates and burners located within said hood to apply heat to said plates, the top of the chamber separating the radiation plates from the interior of the chamber so that the gases within the hood do not contact the yarns moving in the chamber.

3. Apparatus for drying yarns running in parallel re lationship in sheet form that comprises a chamber having a fixed upper portion, a lower portion articulated with the upper portion and movable from a marginally pendant position to a position defining with the upper portion a long interior space of a width not substantially in excess of the width of the sheet to be accommodated and of small height, a pluarlity of combs articulated with said upper portion and movable from a marginally pendant position to a position lying wholly within said upper portion, said combs each having two parallel rows of individually offset teeth and a safety bar movable from a position between said rows of teeth to a position outside of the space between said rows of teeth, sheet guide bars between said combs, alternate guide bars being supported from said upper portion and intermediate guide bars being supported from said lower portion.

4. Drying apparatus as claimed in claim 3 in which the comb and bottom portion are both articulated at the same side of the upper portion.

5. Drying apparatus as claimed in claim 3 in which the teeth of the comb slope upwardly from the free end when the comb is in pendant position.

References Cited in the file of this patent UNITED STATES PATENTS 1,560,589 Andrews et a1 Nov. 10, 1925 2,183,298 Ofien Dec. 12, 1939 2,456,804 Winslow Dec. 21, 1948 2,571,815 Benoit et a1 Oct. 16, 1951 FOREIGN PATENTS 179,832 Great Britain May 18, 1922 

2. APPARATUS FOR DRYING YARNS RUNNING IN PARALLEL RELATIONSHIP IN SHEET FORM THAT COMPRISES A CHAMBER HAVING A LONG INTERNAL SPACE OF A WIDTH NOT SUBSTANTIALLY IN EXCESS OF THE WIDTH OF THE SHEET TO BE ACCOMMODATED AND HAVING SMALL VERTICAL HEIGHT, MEANS TO GUIDE THE YARNS OF THE SHEET WITHIN SAID CHAMBER, MEANS TO ADMIT A HEATING GAS AT A HIGHER TEMPERATURE TO THE WETTEST YARNS AND MEANS TO ADMIT A HEATING GAS AT A LOWER TEMPERATURE TO THE PARTIALLY DRIED YARNS, MEANS TO WITHDRAW THE HEATING GASES AFTER THEY HAVE BEEN PASSED IN COUNTERCURRENT RELATION TO THE DIRECTION OF MOVEMENT OF THE YARNS, A PLURALITY OF RADIATION PLATES EXTENDING LENGTHWISE OF THE TOP OF SAID CHAMBER BETWEEN SAID ADMISSION MEANS AND SAID WITHDRAWAL MEANS, A HOOD COVERING SAID RADIATION PLATES AND BURNERS LOCATED WITHIN SAID HOOD TO APPLY HEAT TO SAID PLATES, THE TOP OF THE CHAMBER SEPARATING THE RADIATION PLATES FROM THE INTERIOR OF THE CHAMBER SO THAT THE GASES WITHIN THE HOOD DO NOT CONTACT THE YARNS MOVING IN THE CHAMBER. 